overview of heavy-ion fusion focus on computer simulation aspect*
DESCRIPTION
Overview of Heavy-Ion Fusion Focus on computer simulation aspect*. Jean-Luc Vay (and many others from the) Heavy-Ion Fusion Virtual National Laboratory Lawrence Berkeley National Laboratory. Computer Engineering Science seminar University of California at Berkeley May 4 , 2004. - PowerPoint PPT PresentationTRANSCRIPT
The Heavy Ion Fusion Virtual National Laboratory
Overview of Heavy-Ion FusionFocus on computer simulation aspect*
Computer Engineering Science seminar
University of California at Berkeley
May 4, 2004
Jean-Luc Vay(and many others from the)
Heavy-Ion Fusion Virtual National Laboratory
Lawrence Berkeley National Laboratory
*This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Berkeley and Lawrence Livermore National Laboratories under Contract Numbers DE-AC03-76SF00098 and W-7405-
Eng-48, and by the Princeton Plasma Physics Laboratory under Contract Number DE-AC02-76CH03073
The Heavy Ion Fusion Virtual National Laboratory
The U.S. Heavy Ion Fusion Program - Participation
Lawrence Berkeley National Laboratory MITLawrence Livermore National Laboratory Advanced CeramicsPrinceton Plasma Physics Laboratory Allied SignalNaval Research Laboratory National ArnoldLos Alamos National Laboratory HitachiSandia National Laboratory Mission ResearchUniversity of Maryland Georgia TechUniversity of Missouri General AtomicStanford Linear Accelerator Center MRTI Advanced Magnet Laboratory Idaho National Environmental and Engineering Lab University of California
a. Berkeley b. Los Angeles c. San Diego
Employees of LBNL, LLNL, and PPPL form the U.S. Virtual National Laboratory for Heavy Ion Fusion
The Heavy Ion Fusion Virtual National Laboratory
Outline
Fusion energy– Principles, advantages/disadvantages– Basic requirements– Paths to fusion
Heavy Ion Inertial Fusion– The target– The chamber– The accelerator– The source
Modeling developments– New physics– New algorithms– Experiment/simulation interface– Data analysis
Conclusion
The Heavy Ion Fusion Virtual National Laboratory
FUSION ENERGY
The Heavy Ion Fusion Virtual National Laboratory
FUSION ENERGY: principles
The Heavy Ion Fusion Virtual National Laboratory
Equivalence of mass and energy
Einstein’s equation
– m = mass of particle– c = speed of light ~ 3.108 m/sec
huge amount of energy can be extracted from mass conversion.
2mcE
Example:
if a 1 gram raisin was converted completely into energyE = 1 gram x c2
= (10-3kg) x (3.108 m/sec)2
= 9.1013 Joules
~ 10,000 tons of TNT!
The Heavy Ion Fusion Virtual National Laboratory
Advantages of fusion
Virtually inexhaustible resources of fuel (water)
Clean (no CO2 emission, almost no radioactive waste)
Fusion reactors are inherently safe. They cannot explode or overheat.
Byproducts or fuel cannot be used to build weapons of mass destruction
The fuel is accessible worldwide
Disadvantages of fusionComplex, still at conceptual stage
Centralization of power sources
The Heavy Ion Fusion Virtual National Laboratory
FUSION ENERGY: Basic requirements
The Heavy Ion Fusion Virtual National Laboratory
Two fundamental forces at play
Holds
Holds
The Heavy Ion Fusion Virtual National Laboratory
In order to fuse, the nuclei have to
overcome electrostatic barrier: go into the right direction:
-50 -40 -30 -20 -10 0 10 20 30 40 50
-0.4
-0.2
0.0
0.2
0.4 electric strong sum
Pot
entia
l (ar
bitr
ary
units
)
distance (arbitrary units)
D
T
D
out
out
In
T
out
Slice view 3D view
need energy (millions of degrees) need many events (many particles)
Find these conditions in?Find these conditions in “PLASMAS”
The Heavy Ion Fusion Virtual National Laboratory
States of matter
The Heavy Ion Fusion Virtual National Laboratory
FUSION ENERGY: Paths
The Heavy Ion Fusion Virtual National Laboratory
The different paths to fusion energy
Tokamaks ITER
Lasers (NIF)
Particle accelerators
“God’s way”“Human ways”
The Heavy Ion Fusion Virtual National Laboratory
HEAVY ION INERTIAL FUSION
The Heavy Ion Fusion Virtual National Laboratory
An Artist’s Conception of a Heavy Ion Fusion Power Plant
From the overall system, we identify several parts and study them separately using theory, experiments and computer simulations.
The Heavy Ion Fusion Virtual National Laboratory
HEAVY ION INERTIAL FUSION: the target
The Heavy Ion Fusion Virtual National Laboratory
For symmetric illumination, the target is enclosed into a capsule
Examples of capsule
Hydrodynamic simulation of target implosion and capsule expansion (Lasnex)
“hybrid”“close coupled”
The Heavy Ion Fusion Virtual National Laboratory
LASNEX is validated against Laser fusion experiments
The Heavy Ion Fusion Virtual National Laboratory
HEAVY ION INERTIAL FUSION: the chamber
The Heavy Ion Fusion Virtual National Laboratory
Inside the chamber
(Lasnex simulation)
(Tsunami simulation)
The Heavy Ion Fusion Virtual National Laboratory
Cut-away view shows beam and target injection paths for an example thick-liquid chamber
The Heavy Ion Fusion Virtual National Laboratory
beam ions Flibe ions electrons
target
3-D BPIC simulation of beam propagating through Flibe
at 27.6 ns; 10 GeV, 210 AMU, 3.125 kA, 5x1013/cm3 BeF2
The Heavy Ion Fusion Virtual National Laboratory
Does plasma neutralization really work?
LSP simulations results for standard bismuth main pulse
1.2-mm waist is acceptable for distributed-radiator target
:
-4 -2 0 2 4y (mm) [simulation]y (mm) [simulation]
-4 -2 0 2 4
y (mm) [experiment] y (mm) [experiment]
0
2
4
6
8 -4 -2 0 2 4
simulation experiment
simulation
experiment
-4 -2 0 2 4
Unneutralized beam Partially neutralized beam
Inte
nsi
ty i
n f
oca
l p
lan
e
400µA, 160 keV, Cs+
Electrostatic quadrupole lenses for beam set-up
Magnetic quadrupoles
for final focusing
Final-Focus Scaled Experiment studied effect of neutralizing electrons (from a hot filament) on focal spot size
LSP particle-in-cell
The Heavy Ion Fusion Virtual National Laboratory
HEAVY ION INERTIAL FUSION: the accelerator
The Heavy Ion Fusion Virtual National Laboratory
Principles of particle acceleratorAcceleration Transverse confinement (magnetic or electric)
(SLAC)
The Heavy Ion Fusion Virtual National Laboratory
High Current Experiment (HCX) began operation January 11, 2002.
10 ES quads
ESQ injector
Marx
matching
diagnostics
diagnostics
High-Current Experiment (HCX): first transport experiment using a driver-scale heavy-ion beam
K+, 1 - 1.8 MeV, 0.2 - 0.6 A, 4 - 10 µs, 10 ES quads, 4 EM quads
HCX is to address four principal issues: – Aperture limits (“fill factor”)? – How maximum transportable current affected by misalignment, beam
manipulations, and field nonlinearities?– beam halo?– effects of gas and stray electrons?
9.44 m
2.51 m 3.11 m 2.22 m 1.38 m
ESQ injector Matching section 10 ES quadsend stationdiagnostics
K+ source
The Heavy Ion Fusion Virtual National Laboratory
3-D WARP simulation of HCX injector
The Heavy Ion Fusion Virtual National Laboratory
HEAVY ION INERTIAL FUSION: the source
The Heavy Ion Fusion Virtual National Laboratory
4 mA/cm2
100 mA/cm2/beamlet
Two possible ion source approaches
Use a large diameter but low current density single-aperture ion source. (traditional)
Extract hundreds of mm-scale high current density beamlets, from a multiple-aperture ion source. (experimental)
The Heavy Ion Fusion Virtual National Laboratory
STS-500 investigating large-aperture diode dynamics
ExptWARP
Warp simulation Experimental results
RisetimePhase Space at End of Diode
The Heavy Ion Fusion Virtual National Laboratory
RZ and transverse slice simulation used to understand parameter space and optimize design
3D used for validation
Physics design with spherical plates completed; iterated with designer to ensure “buildability”
0. 1.5-7.5
7.5
0.5 1.0Z (m)
X (mm)
Current = 0.07 Amps, Final energy = 400 keV
Normalized
emittance
Physics design of 119-beamlet merging experiment on STS500 is complete
The Heavy Ion Fusion Virtual National Laboratory
Parameters Results Status
Current density 100 mA/cm2 (5 mA) met goal
Emittance Teff < 2 eV met goal
Charge states > 90% in Ar+ met goal
Energy spread < a few % beam suffers CX met goal
Beamlets from Argon RF Plasma Source meet the required specifications
Single Beamlet:
Multiple Beamlet:RF Source: Image on Kapton:
The Heavy Ion Fusion Virtual National Laboratory
Merging Beamlet fabrication is in progress
Einzel Lens Test
(STS-100)qualified high gradient insulator (up to 35 kV/cm).
Full-gradient test (STS-500)
vacuum gap voltage gradient (>100kV/cm)
Soon
The Heavy Ion Fusion Virtual National Laboratory
MODELING DEVELOPMENTS
The Heavy Ion Fusion Virtual National Laboratory
Our next-step vision
Beam Science Inertial Fusion Energy
Brighter sources/
injector ESQ Channel
1.2 MV Preaccelerator using Einzel lens focusing for beamlets
0.4 MV beamlet- merging section
1.0 m
7 cm
Maximum <J >, Bn Transport
Beam neutralization
Theory/simulations
Accelerator
Final Focus
Source and injector
NOW NEXT STEP
integrated beam experiment (IBX)
...to test source-to-target-integrated modeling
3
The Heavy Ion Fusion Virtual National Laboratory
The IBX mission is to demonstrate integrated source-to-focus physics
7m25 ns
40 m (10 MeV)
15 m250 25 ns
2 m250 ns 1.7 MeV
Ion: K+ (1 beamline)
Total half-lattice periods: 148
Total length: 64 m5 - 10 MeV
Injector
Accelerator
DriftCompression
Final Focus
Neutraliz
ation
The Heavy Ion Fusion Virtual National Laboratory
We will develop an integrated, detailed, and benchmarked source-to-target beam simulation capability
delta-f, continuum Vlasov, EM PIC
electrostatic / magnetoinductive PIC EM PIC rad -hydroWARP LSP BPIC
BEST SLV LSPdelta-fBEST
Buncher Finalfocus
Chambertransport TargetIon source
& injector Accelerator
The Heavy Ion Fusion Virtual National Laboratory
MODELING DEVELOPMENTS: new physics
The Heavy Ion Fusion Virtual National Laboratory
Electron production missing in simulation of HCX
Beam head hit the structure
The Heavy Ion Fusion Virtual National Laboratory
Toward a self-consistent model of electron effects
Plan for self-consistent electron physics modules for WARP
Key: operational; implemented, testing; partially implemented; offline development
WARP ion PIC, I/O, field solve
fbeam, , geom.
electron dynamics(full orbit; drift)
wall electron source
volumetric (ionization)
electron source
gas module
penetration from walls ambient
charge exch.ioniz.
nb, vb
fb,wall
fb,wall
sinks
ne
ions
Reflectedions
fb,wall
The Heavy Ion Fusion Virtual National Laboratory
WARP and electron cloud code POSINST merged
• the code POSINST, specialized in the prediction of electron clouds in high energy physics accelerator, was merged with WARP
• brings new capabilities and collaborations for study of electron clouds in heavy ion fusion and high energy density physics
• Specialized GUI page added to WARP GUI by UCB UG student– run POSINST
– Read/plot output data
The Heavy Ion Fusion Virtual National Laboratory
New large time-step electron mover reproduces the e-cloud calculation in < 1/25 time
Full-orbit , t=.25/fce Large time-step interpolated
A major invention that should have application to many fields including MFE, astrophysics, near-space physics...
The Heavy Ion Fusion Virtual National Laboratory
MODELING DEVELOPMENTS: new algorithms
The Heavy Ion Fusion Virtual National Laboratory
challenging because length scales span a wide range: m to km(s)
End-to-end modeling of a Heavy Ion Fusion driver
m
m
km
The Heavy Ion Fusion Virtual National Laboratory
The Adaptive-Mesh-Refinement (AMR) method
addresses the issue of wide range of space scales
crosscutting example from CFD
AMR concentrates the resolution around the edge which contains the most interesting scientific features.
3D AMR simulation of an explosion (microseconds after ignition)
The Heavy Ion Fusion Virtual National Laboratory
Particle-In-Cell + AMR applied to HCX source in axisymmetric (r,z) geometry
0.0 0.1 0.2 0.3 0.40.0
0.2
0.4
0.6
0.8
1.0 ngf=1, npf=1 (base grid) ngf=2, npf=4 ngf=4, npf=16 ngf=1, npf=4 (AMR)
4*
no
rma
lize
d R
MS
em
itta
nce
(
mm
.mra
d)
Z(m)
Low res.Medium res.High res.Medium res. + AMR
Z (m)
X (
m)
4 N
RM
S(
mm
.mra
d)
AMR-PIC simulation of ion source
The high res. result is recovered with medium res.+AMR around beam edges at 1/4 of comput. cost
The Heavy Ion Fusion Virtual National Laboratory
Collaboration HIF/CBP and ANAG (Phil Colella’s group) to provide AMR library of tools to Particle-In-Cell codes
Example of WARP-Chombo injector field calculation
The Heavy Ion Fusion Virtual National Laboratory
Vlasov Models offer low noise, large dynamic range
x
px 10-5
10-4
10-3
10-2
10-1
1
Solution of Vlasov equation Solution of Vlasov equation on a grid in phase spaceon a grid in phase space
Courtesy E. Sonnendrucker et al., IRMA, U. of Strasbourg with HIF-VNL
Moving mesh Adaptive mesh
The Heavy Ion Fusion Virtual National Laboratory
MODELING DEVELOPMENTS: interface experiment/simulation
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Nor
mal
ized
X E
mit
tan
ce (
m
m-m
rad
)
20151050
z (m)
self-consistent 2-plane reconstruction after ESQ 3-plane reconstruction after ESQ semigaussian
2.22 m 2.22 m 2.22 m
HCX transport line (10 quads/tank)Matching sectionInjector
2.51 m 3.11 m
We are using simulations to learn what data we need to take, and how best to use the data we obtain
• Simulations initialized using 4D particle distributions synthesized from ESQ-exit slit-scan data (simulated, here) are far better than those using an ideal distribution
• An (x,y) scan, in addition to (x,x) and (y,y), is important
z (m)
No
rmal
ized
x e
mit
tan
ce (-
mm
-mr)
semi-Gaussian
Integrated simulation, starting at source
3-plane synthesisadding (x,y) data
2-plane synthesisusing (x,x) and (y,y)
Optical slit diagnostic is yielding unprecedented information about HCX beam distribution
isosurface where ƒ(x,y,x) = 30% of peak
face-on (xy) view rotated to right
ƒ(y,x) (integ. over x)
line is mean x´(x=0) vs. y
x´
y
shadow of “bridge” across slit
x
u
vy
dzh
• This scanner measures f(x,y,x)• It contains such information as
the (y,y) distribution as a function of x, or averaged over all x
• It can be “gated” in time
Phase-space diagnostics
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MODELING DEVELOPMENTS: data analysis
The Heavy Ion Fusion Virtual National Laboratory
Advanced interactive particle viewer
• High dimensionality (3-D X + 3-D V) data inherently difficult• Collaboration with visualization group for developing new kind of particle viewer
Interactive selection of particles is automatically translated to another view:
A new rendering technique gives compact representation of 6-D data:
The Heavy Ion Fusion Virtual National Laboratory
CONCLUSION
Fusion is a very attractive source of energy– Would solve many problems– But hard to achieve
Still far: there is lot of exciting science to study and technologies to develop
Computer simulation plays a crucial role in studying science, planning and analyzing experiments
The design of a full scale driver will rely heavily on integrated simulation from end-to-end
In order to reach our goal, we are developing new state-of-the-art algorithms for computation and data analysis
For more, visit our home page at http://hif.lbl.gov
The Heavy Ion Fusion Virtual National Laboratory
BACKUP slides
The Heavy Ion Fusion Virtual National Laboratory
3D simulations of IBX
z (m) in fixed-then-moving frame
Beam created at source, matched, accelerated, begins to drift compress.
Parameters:
1.7 6.0 MeV
200 100 ns
0.36 0.68 Amps
4.6 us of beamtime
separatingtail
(C/m)
Mesh frozen
Mesh accelerates with beam
Driftcompression
The Heavy Ion Fusion Virtual National Laboratory
BASIC PLASMA COMPUTER MODELS
The Heavy Ion Fusion Virtual National Laboratory
Computer simulation of plasmas
We compute on various platforms: pc (Pentium, Athlon), Pentium clusters, IBM-SP
IBM-SP very powerful parallel computer but need to simulate systems that contains at least 1000 billions of real particles
Even on the NERSC IBM-SP, the simulation of all the real particles is usually unfeasible
We have to make approximations!
The Heavy Ion Fusion Virtual National Laboratory
Computer simulation of plasma as collection of particles
– We use macroparticles (1 macroparticle = many real particles)– We compute the force (field) on a grid– We advance particle and fields by finite time steps
x
y
The Heavy Ion Fusion Virtual National Laboratory
Computer simulation of plasma as fluid
– A system containing many particles may (under certain conditions) be modeled as a fluid
Example: air is made of molecules but is often described as a fluid
– Restriction: one location = one velocity
– We compute the fluid equation on a grid
– The temporal evolution of the fluid is computed using finite time steps
x
y